Genetic and oceanographic tools reveal high population connectivity and diversity in the endangered pen shell Pinna nobilis

Marlene Wesselmann,Carlos M. Duarte,José R. García-March,Iris E. Hendriks,Lionel Renault,Aschwin H. Engelen,Ester A. Serrão,Mercedes González-Wangüemert

doi:10.1038/s41598-018-23004-2

Abstract

For marine meta-populations with source-sink dynamics knowledge about genetic connectivity is important to conserve biodiversity and design marine protected areas (MPAs). We evaluate connectivity of a Mediterranean sessile species, Pinna nobilis. To address a large geographical scale, partial sequences of cytochrome oxidase I (COI, 590 bp) were used to evaluate phylogeographical patterns in the Western Mediterranean, and in the whole basin using overlapping sequences from the literature (243 bp). Additionally, we combined (1) larval trajectories based on oceanographic currents and early life-history traits and (2) 10 highly polymorphic microsatellite loci collected in the Western Mediterranean. COI results provided evidence for high diversity and low inter-population differentiation. Microsatellite genotypes showed increasing genetic differentiation with oceanographic transport time (isolation by oceanographic distance (IBD) set by marine currents). Genetic differentiation was detected between Banyuls and Murcia and between Murcia and Mallorca. However, no genetic break was detected between the Balearic populations and the mainland. Migration rates together with numerical Lagrangian simulations showed that (i) the Ebro Delta is a larval source for the Balearic populations (ii) Alicante is a sink population, accumulating allelic diversity from nearby populations. The inferred connectivity can be applied in the development of MPA networks in the Western Mediterranean.

Highlights

Understanding marine connectivity is crucial to implement effective conservation measures and designing representative marine protected areas (MPAs) networks[1]
Most of the larvae arriving to Banyuls were greatly influenced by the Northern Current (NC) as they are expected to come from north of this population, except some larvae coming from Cap de Creus and Medes Islands (Fig. 2A)
The NC is not expected to influence the larvae arriving to the Ebro Delta, as the back-tracking model predicted that the larvae arriving there were originated from the coast of the province of Castellon and Columbretes Islands and with a lower probability from Calpe (Alicante) (Fig. 2B)

Summary

Introduction

Understanding marine connectivity is crucial to implement effective conservation measures and designing representative MPA networks[1]. Assessing diversity and connectivity among Pinna nobilis populations is fundamental to help in the design of a network of MPAs for conservation in the Mediterranean Sea. Until now, the genetic structure of the pen shell has only been studied in the Eastern Mediterranean and in the Tyrrhenian and Sardinian Seas using mtDNA16–18 and nuclear[19] DNA sequences (18S and 28S). We aim to (i) study the phylogeographical pattern of P. nobilis in the Mediterranean with mtDNA markers (COI); (ii) assess the genetic diversity of the populations of P. nobilis in the Western Mediterranean Sea using microsatellites; (iii) infer the connectivity pattern between the populations of P. nobilis from the Balearic Islands and the Mediterranean mainland Coast of Spain and France; (iv) identify source and sink populations for this species in the Western Mediterranean Sea; and (v) use this information to suggest areas of conservation priority for a network of marine protected areas

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Conclusion